alcemy EDGE East Side Berlin low-carbon concrete pour

Summary

Highlights

• Alcemy integrates state-of-the-art sensor technology into cement production, automating quality control 🎛️.
• The project reduces carbon emissions by cutting down on clinker in the cement mixture 🌱.
• Collaborating with EDGE and Allianz demonstrates the project's potential and ambition 📈.
• The initiative is pushing the limits of current construction standards while paving the way for more sustainable practices ♻️.
• Despite initial skepticism, the technology has proven reliable, showcasing normal and extreme use case success 🚧.

Key Takeaways

• Alcemy utilizes sensor technology to automate concrete quality control, improving consistency and reducing costs 🚀.
• By reducing clinker use, Alcemy significantly cuts down the CO2 footprint in concrete production 🌍.
• The EDGE East Side Berlin project is a testament to low-carbon concrete's feasibility for modern architecture 🏢.
• Integrating limestone powder proves effective for clinker substitution, helping decarbonize the construction industry 🏗️.
• Alcemy's project achievements include successful implementation under extreme conditions, providing valuable insights for future endeavors 🔬.

Overview

Chapters

• 00:00 - 00:30: Introduction to Alcemy Alcemy introduces sensor technology to cement and ready-mix concrete plants and trucks to automate and enhance quality measurement. By recording data and using intelligent algorithms, Alcemy infers the properties of fresh and hardened concrete as well as cement properties. This automation aims to ensure consistent quality in production, reducing manual measurement, increasing automation, and lowering costs.
• 00:30 - 01:00: Sustainability and CO2 Relevance The chapter discusses the relationship between sustainability and CO2 emissions in the context of concrete production. It highlights that as concrete becomes more sustainable, with less clinker, water, and more recycled materials, it becomes more sensitive to environmental variations. This necessitates rigorous quality monitoring and control, which is partly automated. The chapter also touches on the EDGE project, noting that despite advancements, sustainable concretes are not yet in high demand by building owners.
• 01:00 - 01:30: EDGE Project and Goals The chapter describes the involvement of project developer EDGE and end investor Allianz in a project aimed at reducing the CO2 footprint of concrete. The goal is to produce concrete with minimal cement clinker, which is the primary contributor to the carbon footprint in concrete. The focus is on achieving a low carbon footprint through innovative concrete production methods.
• 01:30 - 02:00: Innovations in Cement and Clinker The chapter discusses innovations in cement and clinker aimed at improving sustainability and cost-effectiveness. It highlights the importance of using cement clinker sparingly rather than maintaining production levels and relying solely on carbon capture technologies. Future changes in standards are expected to improve clinker efficiency, and efforts at EDGE are focused on identifying components where these efficiencies can be implemented under current standards. The chapter emphasizes the role of alcemy technology in exploring the potential of using limestone powder as a clinker substitute and addresses related challenges.
• 02:00 - 02:30: Testing CEM X Binder Concept The chapter discusses the testing of the CEM X binder concept, which involves using higher clinker substitution with limestone filler in concrete. This approach was implemented in practice by adding limestone powder in the ready-mixed concrete plant. The aim was to explore its feasibility under conditions of minimal water and paste content, specifically tested in C40/50 interior components which traditionally use higher cement content than the industry standard. An example application mentioned is the EDGE East Side Berlin, a high-rise building challenged with extreme pumping sections at unusual temperatures.
• 02:30 - 03:00: Challenges in Extreme Conditions The chapter explores the potential of limestone powder as a substitute for clinker in concrete, emphasizing its role in achieving high clinker efficiency in challenging conditions. The goal is to demonstrate that limestone powder can significantly contribute to the decarbonization of concrete construction. The chapter also aims to provide valuable insights for regulatory bodies on the implications of extreme clinker efficiency.
• 03:00 - 03:30: Successful Pump Trials The chapter titled 'Successful Pump Trials' discusses an innovative mix design for EDGE concrete, detailing its composition and successful implementation. Matthias Bartels outlines the specific components used, including 240 kilograms of CEM III/A 42,5 N cement and 125 kilograms of limestone filler, along with a notably low water content of 127 liters. With experience spanning 14 years, he highlights this as the lowest water content achieved in his career. The chapter emphasizes maintaining normative guidelines while innovating upon traditional concrete mix designs.
• 03:30 - 04:00: Pumpability and Limitations The chapter discusses the minimum cement paste requirements for pumpable concretes, specifically mentioning that at least 254 liters is needed. The focus is on the CO2 savings achieved in the EDGE East Side Berlin project, which are mainly attributed to a significant reduction in clinker and water usage. Compared to a conventional C 40/50 concrete, which usually contains 380-400 kg of cement, the project managed to reduce this to 240 kg using CEM III/A cement.
• 04:00 - 05:00: Assembly and Consistency Maintenance The chapter discusses the challenges of using EDGE eco-concrete for the EDGE East Side Berlin project, focusing on the formulation's low water and cement content combined with a high limestone filler content. The specific challenges include maintaining a water binder value of 0.34 under high temperature conditions of 30 degrees Celsius for both air and concrete, while working on a building planned to reach a height of 140 meters and a pumping distance of 280 meters.
• 05:00 - 05:30: Early Strength Achievements The chapter discusses the high demands placed on concrete in constructing slopes and various arcs. Thomas Kunert, an expert in concrete shell construction, shares a positive conclusion. He expresses surprise and optimism following preliminary discussions, continuous involvement in the construction process, and after a successful pump trial.
• 05:30 - 06:30: Challenges and External Factors The chapter titled 'Challenges and External Factors' discusses the current advancements and performance of a construction project. The speaker shares optimism about the project's progress, specifically mentioning that the pumping of concrete slabs has proceeded smoothly and effectively. The first slab was successful, with a smooth surface and minimal cracks, leading to a positive outlook on the concrete used. The narrative concludes with a prompt for Leopold Spenner to provide his perspectives on the concrete's pumpability as per the project consortium's evaluation.
• 06:30 - 07:30: Experience with Alcemy Technology The chapter titled 'Experience with Alcemy Technology' discusses an experiment in which 100m³ of concrete was successfully pumped at a speed of 25m³/h and a pressure of 80 bar over a distance of 280m, including bends and inclines, despite the challenging temperature of 30 degrees celsius. The chapter also highlights challenges encountered, such as the concrete's thixotropy and the need for additional shear energy to reinitiate flow after the concrete had rested for a long period in high temperatures, leading to the formation of an 'elephant skin.'

alcemy EDGE East Side Berlin low-carbon concrete pour Transcription

• 00:00 - 00:30 What exactly does alcemy do? Alcemy brings sensor technology to cement plants, ready-mix concrete plants and ready-mix concrete truck mixers. With this, we try to measure the quality, record data, then use intelligent algorithms in the background to infer the fresh and hardened concrete properties, the cement properties. Instead of having to measure everything manually. This makes it easy to achieve a more consistent quality in production. More automation, less costs and all that is the idea of Alcemy.
• 00:30 - 01:00 What does this have to do with CO2? One can say that the more sustainable the concrete becomes, the less clinker, and also the less water, the more recycled building rubble, the more sensitive the concrete becomes to variations from the external environment. And then the end-to-end quality monitoring that we do and the partly automated control becomes essential. How is this related to the EDGE-project? We have simply found that sustainable concretes are not yet demanded in larger quantities, from the building owners,
• 01:00 - 01:30 from the building owners, from the demand side. And that's why we approached a project developer EDGE and an end investor Allianz, directly. We explained to them what is possible in concrete today, how much one can reduce the CO2 footprint, and that resulted in this project. What do EDGE and alcemy want to achieve in this project? The cement clinker is responsible for the carbon footprint of the concrete, and that's why our goal in the project was to produce a concrete with as little cement clinker as possible, and thus with a very low carbon footprint. Because it is always more
• 01:30 - 02:00 sustainable and also more cost-effective to use cement clinker more sparingly than to produce unchanged quantities of cement clinker and then simply capture the CO2 by carbon capture. In the next few years, many standards will be loosened, which will enable significantly more clinker efficiency. At EDGE, we have been looking for components where exactly this can already be implemented within the standard, even if only for a small percentage of concrete components. For the development of the alcemy technology, it is really important to get a glimpse of how far limestone powder can be pushed as a clinker substitute and what problems then arise.
• 02:00 - 02:30 And that's how we came across C40/50 interior components, because much higher cement contents are used there today than prescribed by the industry standard. Thus, by adding limestone powder in the ready mixed concrete plant, it was possible to test the CEM X binder concept – that allows higher clinker substitution with limestone filler – in practice, directly in the absolute limit range of water and paste content. EDGE East Side Berlin - a high-rise building with extreme pumping sections at extreme temperatures - this could be
• 02:30 - 03:00 called the ultimate litmus test for any concrete. If the concrete works here, it’d be a proof that limestone powder as a clinker substitute and clinker efficiency in general are capable of much more than currently envisaged in the VDZ roadmap. We therefore hope that the project will be an important milestone for the use of limestone powder to decarbonize concrete construction and will also provide many insights for e.g. regulatory bodies which critical situations arise from extreme clinker efficiency.
• 03:00 - 03:30 Matthias Bartels, what is the exact composition of EDGE concrete? The normative minimum cement content for indoor components is 340 kilograms. This was also the basis for us to stay within the normative range. In other words, the mix design is equipped with 240 kilograms of CEM III/A 42,5 N, plus 125 kilograms of limestone filler. And everything in total with 130 liters of water addition, adjusted by admixtures we are even at 127 liters. And in the 14 years of my career so far, this is, the lowest water content which I have seen being realized.
• 03:30 - 04:00 We are at 255 liters of cement paste, 254, which is also the minimum requirement for concretes that have to be pumped. How do the CO2 savings actually come about with the EDGE East Side Berlin? The CO2 savings originate, of course, mainly through drastic reduction of clinker and water. If you look at a conventional C 40/50, they usually contain around 380, 400 kilograms of cement. As I said, we only have 240 kilograms and a CEM III/A cement.
• 04:00 - 04:30 What is the challenge in using the EDGE eco-concrete for the EDGE East Side Berlin? The challenge with the concrete is of course the low water content in combination with the low cement content and high high limestone filler content. And being able to work with that concrete with a water binder value of 0,34, with temperatures of 30 degrees air and 30 degrees concrete over long times is a huge challenge. We have an object with a planned building height of 140 meters. We have a pumping distance of 280 meters with downward
• 04:30 - 05:00 slopes and various arcs. And this poses the most extreme requirements to the concrete. Thomas Kunert, as an expert in concrete shell construction, what is your overall conclusion? Well, my conclusion is very, very positive. I have to say that I was really surprised. But after the preliminary discussions that we had, and being involved in the process and all your research from the beginning, and after the successful pump trial that we
• 05:00 - 05:30 did in preparation, I was very optimistic and I have now been confirmed in my assumptions that it works well. And we are already pouring the second slab, it's almost finished. We pumped the first slab, which went very well. The surface of the concrete, as it looks now, is beautiful, in contrast to the slabs that we concreted before. Those aren't bad either, but these are just nicer. Very smooth, hardly any cracks. So as I said, I'm very positive about this concrete. Leopold Spenner, what is the conclusion on the subject of pumpability from the project consortium?
• 05:30 - 06:00 In principle, everyone involved was surprised at how well the concrete could generally be pumped. On August 5th and 6th, we pumped a total of just under 100m³ of concrete at a speed of about 25 m3/h approximately at 80 bar, which is really respectable for the pumping distance of 280m with all the bends and inclines, especially since it was also 30 degrees warm, so this was a really good result. We could experience the limitations of the concrete as well, e.g. the thixotropy, if the concrete rests very long at very hot temperatures, then one needed shear energy to get it to flow again. We could observe an elephant skin formation, as the
• 06:00 - 06:30 concrete is so water-deprived at the surface that the surface dries out fast and when the concrete flows over surfaces, then layers form where the concrete clogs. And that led to the fact that on days where really everything came together, high temperatures, narrower pumping pipes, long standing times, and lower flow spreads, that on such days we had stoppages and problems with the pumping. But it would also have been weird if we hadn't found the limits of the concrete; and in principle this is a really good sign that we
• 06:30 - 07:00 were able to pump the concrete. And besides, experiencing the limits is very instructive for the further development of concrete. Thomas Kunert, how well could you use the concrete for assembly? There are also positive things to report. You might see something in the background. So it can be assembled wonderfully. The colleagues can strip it off nicely. There is no water settling, no puddles or anything. The top layer of the steel rebar is nicely covered. One might think with the flow spreading up to 64, 65 cm, that the concrete might sink in.
• 07:00 - 07:30 But this concrete stands up perfectly. Which you can also see in the great surfaces that I praised a lot before. Matthias Bartels, how do you assess the issue of maintaining consistency in these hot temperatures? I think that also convinced everyone on the construction site that with the long waiting times and the temperatures we were able to realize a stiffening of only four to maximum of five centimeters over two hours and more, which is really exceptional in my experience. Thomas Kunert, how do you assess the issue of early strength with such low clinker contents?
• 07:30 - 08:00 That was really one of our big concerns, that we might lose time due to long concrete curing times at the construction site, that we e.g. would have to wait to be able to move our protective shields upwards, or wait to mount the vertical struts of our precast elements. Yes, we had our concerns, but they were all dismantled: Before the actual pour already through the laboratory tests, and then during the pour we made strength cubes, crushed them day by day, we had 23 kN/mm2 after three days, 31 kN/mm2 after four days, and that was just perfect for our schedule,
• 08:00 - 08:30 so that we didn’t loose any time. So the critical issue of early strength also works well. What were the biggest challenges and shortcomings? We have already noticed that external factors play a very big role, i.e. external factors that you can't necessarily foresee, can't plan in advance. And you can see, we noticed that the concrete is even more sensitive than a robust, regular one.
• 08:30 - 09:00 We found that it’s very likely caused by the consistency, the flow spread. Once we get to 63, 64 mm of flow spread, the concrete works great. But if we miss this narrow corridor, it becomes very difficult. And that's the goal with the alcemy technology to get the concrete to the construction site so that it has exactly the required consistency that we need for assembly. How is your first experience of the alcemy technology?
• 09:00 - 09:30 Well, my personal opinion is that the technology itself certainly works. Because when I looked at your or my colleagues’ phones, I saw that the technology was working: predicted flow spread, and actually measured flow spread was very similar. And apart from that, I am convinced that we need such technology to be able to process such sensible concretes, i.e. to get them to the construction site just in the desired quality corridor, because with the normal concrete mix designs,
• 09:30 - 10:00 they are very forgiving, they are very robust to variations. This sustainable type of concrete, I would say skinny concrete, i.e. little water, little cement, lots of admixtures, it reacts sensitively and differently, and, above all, abruptly. So that's something we still have to work on. Matthias Bartels, what is your interim summary of the alcemy technology?
• 10:00 - 10:30 Well, I have to be honest and say that I was impressed by the technology. Yes, I was skeptical, I'd say, that the real world could be mapped so easily. But I gradually took on the work with the app and saw that the predicted flow spreads on the construction site were actually accurate, except for plus/minus one or two centimeters. And what also convinced me is that
• 10:30 - 11:00 everyone involved always has an immediate insight into what is happening. Yes, that is really the amazing thing, that one has end-to-end monitoring of the flow spreads and how they change in-transit. You can see water dosages when they happen. So this gray area that we have today, that disappears. You have control. So we have certainly set an absolute milestone in my experience. I don't know of any comparable projects that have been implemented so far. There may be some other pilot projects in the entire world, but for me and everyone involved,
• 11:00 - 11:30 this was a breakthrough project and I think it's really cool that we were able to implement it in such a way and that the willingness was there.